On Thursday, in a confirmation hearing in which nearly every senator, Democrat and Republican, heaped glowing praise upon their colleague John Kerry, D- Mass., who's been nominated for secretary of state, Sen. Rand Paul, R-Ky., posed contentious questions to Kerry about the U.S.'s role on the world stage. It quickly became apparent that the two senators not only had different political opinions, but different world views. Rand seems to see the world in absolutes; Kerry maintains intervention in world affairs be judged on a case-by-case basis.

Paul, who was publicly critical of President Obama's authorizing U.S. action in Libya to help depose Mohamar Gadhafi, wanted to know Kerry's take on a president's authorizing military action without congressional approval. Kerry responded that, although he is a strong supporter of the War Powers Act, which requires the president to seek congressional authority to declare war, he also supports the right of a president to act in an emergency.

"I supported Ronald Reagan when he sent troops into Grenada. I supported George H.W. Bush when he sent troops into Panama. I supported President Clinton when, against the will of the Congress, he did what was needed to be done in Kosovo and Bosnia, so forth. And in this particular instance, I think the president behaved in that tradition," said Kerry.

Paul suggested Kerry is cherry-picking the Constitution. He pointedly asked Kerry to defend his anti-war stance in the 1970s against Richard Nixon's decision to bomb Cambodia, on the one hand, and President Obama's actions in Libya on the other. Kerry responded that the circumstances of the conflicts were different: Vietnam had been waging for years without Congressional approval, unlike the situation in Libya.

Paul was unmoved.

"Length of time, but similar circumstances: a bombing campaign unauthorized by Congress," he said. "See, the Constitution really doesn't give this kind of latitude to sometimes go to war and sometimes not go to war."

Kerry said he respected that position in theory, but in practice always requiring Congressional approval for every military action was not practical.

"You can be absolutist and apply it to every circumstance. The problem is, it just doesn't work in some instances," said Kerry. "When 10,000 people are about to be wiped out by a brutal dictator and you need to make a quick judgment about engagement, you certainly can't rely on a Congress that has proven itself unwilling to move after weeks and months."

The two men went on to spar over aid to Egypt, given Egyptian president Mohamed Morsi's comments from 2010 that have recently been made public calling Israelis "blood suckers" and "descendants of apes and pigs."

Kerry called the comments "reprehensible" but again pointed to the fact that Egypt remains a critical lynchpin for a peaceful Middle East. The senator also pointed to the ways Morsi's administration has been helpful - supporting the peace agreement with Israel and working with the U.S. on security in the Sinai peninsula.

"This is always the complication in dealings in the international sector - not everything lends itself to a simple clarity, black/white, this/that every time," said Kerry.

Paul also pressed Kerry on whether he would support cutting Pakistan's aid if the country does not free Shakil Afridid, the Pakistani doctor serving 33 years in prison who was convicted of running a vaccine program in Abbottabad to help the U.S. obtain DNA from Osama bin Laden's relatives. Paul said Dr. Afridi's detention could act as a deterrent for future informants and that Pakistan, as an ally, should be cooperating.

Kerry again said that the relationship with Pakistan is complex, and pointed out the other ways the country has helped the U.S. in its war against terror.

"I intend to raise the issue of Dr. Afridi with them. I can promise you that," said Kerry. "But I am not going to recommend, nor do I think it is wise, for American policy to just cut our assistance. We need to build our relationship with the Pakistanis, not diminish it. "